Differential roles of NHERF1, NHERF2, and PDZK1 in regulating CFTR-mediated intestinal anion secretion in mice

• Published in: The Journal of clinical investigation Vol. 119; no. 3; pp. 540 - 550
• Main Authors: Singh, Anurag Kumar, Riederer, Brigitte, Krabbenhöft, Anja, Rausch, Brigitte, Bonhagen, Janina, Lehmann, Ulrich, de Jonge, Hugo R, Donowitz, Mark, Yun, Chris, Weinman, Edward J, Kocher, Olivier, Hogema, Boris M, Seidler, Ursula
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.03.2009
• Subjects: Ablation; Adapter proteins; Adrenergic receptors; Animals; Anions - metabolism; Bicarbonates - metabolism; Binding proteins; Biomedical research; Cell Membrane - physiology; Cell receptors; Colforsin - antagonists & inhibitors; Colforsin - pharmacology; Cystic Fibrosis Transmembrane Conductance Regulator - physiology; Duodenum - secretion; Epithelial Cells - drug effects; Epithelial Cells - physiology; Gene Deletion; Intestinal Secretions - physiology; Intracellular Signaling Peptides and Proteins - deficiency; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - physiology; Ion channels; Kinases; Lysophospholipids - pharmacology; Mice; Mice, Knockout; Phosphoproteins - deficiency; Phosphoproteins - genetics; Phosphoproteins - physiology; Physiological aspects; Receptors, Adrenergic, beta-2 - drug effects; Receptors, Adrenergic, beta-2 - physiology; Small intestine; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - physiology; United States
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/jci35541

The epithelial anion channel CFTR interacts with multiple PDZ domain-containing proteins. Heterologous expression studies have demonstrated that the Na+/H+ exchanger regulatory factors, NHERF1, NHERF2, and PDZK1 (NHERF3), modulate CFTR membrane retention, conductivity, and interactions with other transporters. To study their biological roles in vivo, we investigated CFTR-dependent duodenal HCO3- secretion in mouse models of Nherf1, Nherf2, and Pdzk1 loss of function. We found that Nherf1 ablation strongly reduced basal as well as forskolin-stimulated (FSK-stimulated) HCO3- secretory rates and blocked beta2-adrenergic receptor (beta2-AR) stimulation. Conversely, Nherf2-/- mice displayed augmented FSK-stimulated HCO3- secretion. Furthermore, although lysophosphatidic acid (LPA) inhibited FSK-stimulated HCO3- secretion in WT mice, this effect was lost in Nherf2-/- mice. Pdzk1 ablation reduced basal, but not FSK-stimulated, HCO3- secretion. In addition, laser microdissection and quantitative PCR revealed that the beta2-AR and the type 2 LPA receptor were expressed together with CFTR in duodenal crypts and that colocalization of the beta2-AR and CFTR was reduced in the Nherf1-/- mice. These data suggest that the NHERF proteins differentially modulate duodenal HCO3- secretion: while NHERF1 is an obligatory linker for beta2-AR stimulation of CFTR, NHERF2 confers inhibitory signals by coupling the LPA receptor to CFTR.